Cycling Female Rats Research Articles

Effect of Prenatal Exposure to Progesterone on Dams and Fetus Health in Albino Rats

This study investigated the effect of progesterone on the pregnant dams health and their offsprings teratology. Eighteen cyclic female rats were used in the study. They introduced to males in the proestrus stage for mating. The pregnant rats were divided into two groups; control group (n=9) and progesterone-treated group, which given progesterone 10 mg/kg starting from the first gestation day (GD1) till 19th day of gestation (GD19). The body weight gain of pregnant dams was monitored. The blood biochemical parameters as serum activities of alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and Gamma-glutamyl transferase (GGT) as well as the levels of urea and creatinine for dams at GD19. Hepatic malondialdehyde (MDA) and reduced glutathione (GSH) were determined. Serum interleukin-6 (IL-6) and tumor necrosis factor- alpha (TNF-α) were monitored for dams at GD19. The fetal weight, cervical vertebral length (CVL) and placental weight were recorded. Fetal stain to the skeleton by Alizarin Red S stains was done. Finally histopathological changes for maternal as well as fetal liver and kidney. The treatment with progesterone resulted in significant (P<0.05) increase in all blood biochemical parameters than control. Hepatic MDA was significantly (P<0.05) increased however, GSH was reduced (P<0.05) in progesterone-treated group than control. Serum IL-6 was also increased (P<0.05) in progesterone-treated dams than control while TNF-α was non significantly altered. Fetal weight and CVL was significantly (P<0.05) reduced beside the presence of some skeletal malformations in progesterone-treated group while placental weight was non significantly altered. The liver and kidney showed various degrees of retrogressive changes in progesterone-treated group. Progesterone adversely affected mothers' health and their foeti.

Expression and function of nesfatin-1 are altered by stage of the estrous cycle

Nesfatin-1 is a peptide derived from the nucleobindin 2 (Nucb2) precursor protein that has been shown to exert potent effects on appetite and cardiovascular function in male animals. Sex hormones modulate the expression of Nucb2 in several species, including goldfish, mouse, and rat, and human studies have revealed differential expression based on male or female sex. We therefore hypothesized that the ability of nesfatin-1 to increase mean arterial pressure (MAP) would be influenced by stage of the estrous cycle. Indeed, we found that in cycling female Sprague-Dawley rats, nesfatin-1 induced an increase in MAP on diestrus, when both estrogen and progesterone levels are low but not on proestrus or estrus. The effect of nesfatin-1 on MAP was dependent on functional central melanocortin receptors, because the nesfatin-1-induced increase in MAP was abolished by pretreatment with the melanocortin 3/4 receptor antagonist, SHU9119. We previously reported that nesfatin-1 inhibited angiotensin II-induced water drinking in male rats but found no effect of nesfatin-1 in females in diestrus. However, nesfatin-1 enhanced angiotensin II-induced elevations in MAP in females in diestrus but had no effect on males. Finally, in agreement with previous reports, the expression of Nucb2 mRNA in hypothalamus was significantly reduced in female rats in proestrus compared with rats in diestrus. From these data we conclude that the function and expression of nesfatin-1 are modulated by sex hormone status. Further studies are required to determine the contributions of chromosomal sex and individual sex hormones to the cardiovascular effects of nesfatin-1.

Sexual dimorphism, estrous cycle and laterality determine the intrinsic and synaptic properties of medial amygdala neurons in rat.

The posterodorsal medial amygdala (MePD) is a sex steroid-sensitive area that modulates different social behavior by relaying chemosensorial information to hypothalamic nuclei. However, little is known about MePD cell type diversity and functional connectivity. Here, we have characterized neurons and synaptic inputs in the right and left MePD of adult male and cycling female (in diestrus, proestrus or estrus) rats. Based on their electrophysiological properties and morphology, we found two coexisting subpopulations of spiny neurons that are sexually dimorphic. They were classified as Class I (predominantly bitufted-shaped neurons showing irregular spikes with frequency adaptation) or Class II (predominantly stellate-shaped neurons showing full spike frequency adaptation). Furthermore, excitatory and inhibitory inputs onto MePD cells were modulated by sex, estrous cycle and hemispheric lateralization. In the left MePD, there was an overall increase in the excitatory input to neurons of males compared to cycling females. However, in proestrus, the MePD neurons received mainly inhibitory inputs. Our findings indicate the existence of hemispheric lateralization, estrous cycle and sexual dimorphism influences at cellular and synaptic levels in the adult rat MePD.

The Role of the Basolateral Amygdala Projections to the Bed Nucleus of the Stria Terminalis in Anxiety‐like Behaviors in Male and Female Rats

Men and women display different symptomology in anxiety disorders, yet our understanding of the sex differences in the neurobiology related to these disorders is limited. The basolateral amygdala (BLA) is a critical component of the neurocircuitry involved in anxiety, is hyperactive in patients with anxiety disorders and displays a sexual dimorphism with respect to neural activity. Differences in BLA activity may be a contributing factor to sex differences in the pathophysiology of anxiety disorders. Prior studies have demonstrated that sex differences in BLA neuronal activity exist; however, it is not known whether specific subsets of BLA neurons exhibit this disparity. BLA outputs to the lateral bed nucleus stria terminalis (BSTL) play a critical role in the expression of prolonged cued fear and general anxiety‐like behavior with female rats expressing less general anxiety‐like behaviors compared to males. The purpose of this study was to determine if BLA‐BSTL neurons in female rats are less active than in males. We utilized in vivo single‐unit extracellular electrophysiological recordings to record anti‐dromically identified BLA‐BSTL neurons in anesthetized male and cycling female rats. We found that BLA‐BSTL neurons in females have lower firing frequencies compared to males, despite females having greater spontaneous BLA neuronal activity overall. We also examined whether prolonged cued fear conditioning, which is dependent, in part, on BLA‐BSTL connections, is less robust in female rats compared to males. Rats were conditioned to an 8 min tone, during which footshocks (0.3mA) were delivered at random. Four days later (when females were in the same estrous stage as training), rats were tested in a novel context and time spent freezing during the presentation of the tone was measured. No sex differences were observed during training, but proestrous females froze less during training compared to males and metestrous females. However, during extinction, females extinguished freezing behavior more quickly than males, and proestrous females froze less than metestrous females. To determine if our electrophysiological data suggesting decreased BLA‐BSTL activity in females leads to a decreased freezing behavior during prolonged cued fear, we utilized a chemogenic approach to selectively inhibit BLA‐BSTL neurons. We performed bilateral Cre‐dependent designer receptor exclusively activated by designer drug (DREADD) injections then assessed anxiety‐like behavior and freezing responses during prolonged cued fear. Preliminary results suggest that inhibition of BLA‐BSTL neurons during the open field task has opposite effects in male and female rats. Specifically, we found that BLA‐BSTL inhibition reduced latency to enter the center in males, but increased latency to enter center in females. Together this suggests that in addition to BLA‐BSTL neurons displaying sex differences in activity, these same neurons may also mediate different behaviors in male and female rats. These results may help explain the apparent disconnect between overall sex differences in BLA neuronal firing and its relation to particular anxiety behaviors.Support or Funding InformationR01MH100536This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

High-Protein Diet Ameliorates Arsenic-Induced Oxidative Stress and Antagonizes Uterine Apoptosis in Rats

Arsenic toxicity purportedly threats a broad spectrum of female reproductive functions. We investigated the remedial role of a casein- and pea protein-enriched high-protein diet (HPD) in combating the arsenic insult. Cyclic female rats maintained on standard diet (n = 6) or an isocaloric HPD (n = 6) were gavaged with As2O3 at 3mg/kg BW/rat/day (n = 12) for 28days. Vehicle-fed rats (n = 6) maintained on the standard diet served as the control. We monitored the estrus cycles and performed the histomorphometric analyses of the uterus and ovary. Uterine luminal epithelial (ULE) ultrastructure was appraised by scanning electron microscopy. Uterine oxidative stress was evaluated in the forms of ROS generation and activities of the ROS scavengers. The uterine apoptotic manifestation was blueprinted by Western blot analysis of caspase-3 and Bax expression. Arsenic treatment arrested the follicular maturation and disrupted the estrus cycles with a typical increase in the diestrus index. Shrunken endometrial glands and thinned microvilli density of the ULE reflected loss of cell polarity and mislaid uterine homeostasis. Increased ROS generation and attenuated activities of the ROS scavengers marked a state of uterine oxidative imbalance and loss of redox regulation. Superfluous expression of procaspase-3, cleaved caspase-3, and Bax mirrored an inflated state of uterine apoptosis. HPD supplementation, by and large, counteracted these arsenic impacts and maintained the frameworks close to the control levels. In conclusion, arsenic mediates its reproductive toxicity, at least in part, by upsetting the uterine ROS homeostasis and redox regulation. Pea proteins and casein-supplemented HPD can counteract the arsenic effects and maintain the reproductive functions.

Hepatic effects of long-term tamoxifen administration to cycling female rats.

The metabolic implications of tamoxifen (TAM) used as preventive therapy of young premenopausal women with high risk of breast cancer is unknown. To unravel this problem, an animal model of long-term TAM administration to cycling young adult female rats was used to evaluate its effects in the liver. Body weight and food consumption were monitored, and at the end of the study, both parameters were lower in TAM-treated rats. Biochemical measurements showed that the TAM administration induced alterations in serum levels of liver enzymes when compared with control rats at different stages of the estrous cycle. In TAM-treated rats, lower glycogen storage was observed in hepatocytes close to the portal areas and pericentrolobular cells had a higher concentration of glycogen. Liver sections of TAM-treated rats presented mild steatosis-a high percentage of area occupied by lipid droplets in the hepatocytes. These results point to metabolic changes upon long-term TAM therapy.

Soy Isoflavones Ameliorate Metabolic and Immunological Alterations of Ovariectomy in Female Wistar Rats: Antioxidant and Estrogen Sparing Potential.

Hormone replacement therapy (HRT) can alleviate estrogen deficiency symptoms especially during menopause. The present study aimed at investigating the effect of soy isoflavones as HRT on immunological and bone health-related parameters with a special focus on the interactions between immunological status and metabolism. Thirty healthy cyclic female Wistar rats were used in this experiment. Ten females were sham-operated, and 20 females were subjected to ovariectomy. Overiectomized (OVX) female rats were randomly divided into 2 groups: the control group (G1, OVX/casein) was fed a casein-based diet, and the second group (G2, OVX/soy) was fed a high soy isoflavone diet. Both groups were compared to a sham-operated group (G3, sham/casein). Treatments continued for 7 weeks. Feed intake, weight gain, and lymphoid organ relative weights were recorded. Some metabolic, immunological, and bone health-related parameters were measured. Moreover, nitric oxide (NO), malondialdehyde (MDA), and total antioxidant capacity (TAC) were determined. Bone histopathology and immunohistochemistry to estrogen receptor alpha (ERα) were done. Feeding soy to OVX females reduced feed intake, weight gain, relative lymphoid organ weight, and T-lymphocytes transformation. Soy isoflavone administration normalized nearly all metabolic and immunological parameters to a level comparable to the sham group via oxidative stress amelioration and bone ERα promotion. Soy isoflavones seemed to be good HRT in estrogen deprivation which modulated the appetite, weight gain, lipid profile, proinflammation, and bone turnover.

Ovarian immunohistochemical expression of estradiol 17β in cyclic female rats treated with steroid free bovine follicular fluid antiserum

Ovarian immunohistochemical expression of estradiol 17β in cyclic female rats treated with steroid free bovine follicular fluid antiserum

Evaluation of progressive hepatic histopathology in long-term tamoxifen therapy

Tamoxifen (TAM) therapy is the better treatment for breast cancer and the drug use the prophylaxis of this disease in young premenopausal women. Yet, the effects associated with this therapy are unknown. To better understand the extension of this problem, we developed an animal model to mimic this therapy, aiming to evaluate its potential biochemical and histopathological changes in the liver. Young cycling female rats were treated with TAM for one, two and three months and toxicological biomarkers and liver histomorphometry were evaluated. Starting at two months, TAM-treatment prevented the normal age-dependent increase in body weight, without inducing changes in food intake. Serum levels of cholesterol and of the metabolic enzymes creatine kinase and aspartate aminotransferase were reduced in all TAM treatment periods. Serum levels of the metabolic enzymes alkaline phosphatase and lactate dehydrogenase were increased after the first month but returned to control levels upon 3 months of drug exposition. Moderate microvesicular steatosis, classified only at the first month of TAM treatment, was reduced afterwards. Our model showed an adaptive response of liver upon 3 months of treatment, suggesting that at the stated conditions, TAM will not promote hepatotoxicity. In this way, the present model may be useful in the study of possible key endocrine effects of TAM use and the search for better clinical outcomes.

Impact of strain, sex, and estrous cycle on gamma butyrolactone-evoked absence seizures in rats

Childhood absence epilepsy (CAE) is the most common pediatric epilepsy syndrome and is characterized by typical absence seizures (AS). AS are non-convulsive epileptic seizures characterized by a sudden loss of awareness and bilaterally generalized synchronous 2.5–4 Hz spike and slow-wave discharges (SWD). Gamma butyrolactone (GBL) is an acute pharmacological model of AS and induces bilaterally synchronous SWDs and behavioral arrest. Despite the long use of this model, little is known about its strain and sex-dependent features. We compared the dose-response profile of GBL-evoked SWDs in three rat strains (Long Evans, Sprague-Dawley, and Wistar), and examined the modulatory effects of estrous cycle on SWDs in female Wistar rats. We evaluated the number of seizures, the cumulative time seizing, and the average seizure duration as a function of dose, strain, and sex/estrous phase. Long Evans rats displayed the greatest sensitivity to GBL, followed by Wistar rats, and then by Sprague-Dawley rats. GBL-evoked SWDs were modulated by estrous cycle in female rats, with the lowest sensitivity to GBL occurring during metestrus. Wistar rats showed the greatest variability as a function of dose, and the least variability within dose; these features make this strain desirable for interventional studies. Moreover, our finding that the SWD response to GBL differs as a function of estrous cycle underscores the importance of cycle monitoring in studies examining female animals using this model. Together, these strain and sex-dependent findings provide guidance for future studies.

The Neural Signals of the Superior Ovarian Nerve Modulate in an Asymmetric Way the Ovarian Steroidogenic Response to the Vasoactive Intestinal Peptide.

The superior ovarian nerve (SON) provides neuropeptide-Y, norepinephrine and vasoactive intestinal peptide (VIP) to the ovaries. Ovarian steroidogenesis is modulated by the SON. In the cyclic rat, the acute steroidogenic response to ovarian microinjection of VIP is asymmetric and varies during the estrous cycle. In the present study, we analyze whether the differential effects of VIP in each ovary are modulated by the neural signals arriving through the SON. Cyclic female rats were submitted on diestrus-1, diestrus-2, proestrus, or estrus to a unilateral section of the SON, and immediately afterward, the denervated ovary was either microinjected or not with VIP. Animals were sacrificed 1 h after treatment. The injection of VIP into the left denervated ovary performed on diestrus-1 decreased progesterone levels in comparison with the left SON sectioning group; similar effects were observed on proestrus when VIP was injected into either of the denervated ovaries. Compared to the left SON sectioning group, VIP treatment into the left denervated ovary on diestrus-2 or proestrus decreased testosterone levels, whereas on diestrus-1, proestrus or estrus, the same treatment resulted in higher estradiol levels. Compared to the right SON sectioning group, VIP injected into the right denervated ovary yielded higher testosterone levels on diestrus-1 and estrus and lower testosterone levels on proestrus. VIP injection into the right denervated ovary increased estradiol levels on diestrus-2 or estrus while decreasing them on proestrus. Our results indicate that in the adult cyclic rat, the set neural signals arriving to the ovaries through the SON asymmetrically modulate the role of VIP on steroid hormone secretion, depending on the endocrine status of the animal. The results also support the hypothesis that the left and right ovary respond differently to the VIPergic stimulus.

Chronic cholestasis is associated with hypogonadism and premature ovarian failure in adult rats (cholestasis causes ovarian hypogonadism)

ABSTRACTHypogonadism is a well-known complication in males with chronic liver diseases. However, the consequences of chronic hepatopathies on female reproductive capacities have received relatively little attention. The present study evaluates the effect of chronic obstructive jaundice on the ovary of adult cycling rats. Estrous cyclicity was monitored to check the functional status of the hypothalamic–pituitary–ovarian axis. Ovarian changes were assessed using histomorphometric, immunohistochemical, and ultrastructural techniques. Chronic cholestasis was associated with estrous cycle irregularities, diminished ovarian weight, primordial follicle loss, atretic follicle prevalence, marked stromal fibrosis, and diminished immunoexpression of proliferation marker and estrogen receptors, in addition to many ultrastructural alterations in theca, granulosa cells, and oocytes of antral follicles. The results establish that chronic cholestasis causes hypogonadism and premature ovarian insufficiency in adult cycling female rats.

Lycopene: Hepatoprotective and Antioxidant Effects toward Bisphenol A-Induced Toxicity in Female Wistar Rats.

Bisphenol A (BPA)—an endocrine disruptor xenoestrogen—is widely spread in the environment. Lycopene (LYC) is an antioxidant phytochemical carotenoid. The hereby study was designed to verify the deleterious effect of BPA on cyclic female rats' hepatic tissue as well as evaluation of the effect of LYC toward BPA hepatic perturbation. Twenty-eight female Wistar rats were allocated equally into four groups: control group, LYC group (10 mg/kg B.wt), BPA group (10 mg/kg B.wt), and BPA + LYC group (the same doses as former groups). The treatments were given daily via gavage to the rats for 30 days. The rats in BPA displayed high activities of serum liver enzymes with low levels of total proteins (TP) and albumin. Moreover, BPA induced hepatic oxidative stress via depletion of antioxidant enzymes concomitant with augmentation of lipid peroxidation, increased comet tail DNA %, and overexpression of caspase-3. Meanwhile, LYC administration reduced the cytotoxic effects of BPA on hepatic tissue, through improving the liver function biomarkers and oxidant-antioxidant state as well as DNA damage around the control values. These findings were confirmed by hepatic histopathological examination. Finally, LYC credited to have a noticeable protective effect versus BPA provoked oxidative injury and apoptosis of the liver tissue.

Comparative effect of anti-inhibin and eCG-hCG supplementation on reproductive hormonal profile in virgin cycling female rats.

Comparative effect of anti-inhibin and eCG-hCG supplementation on reproductive hormonal profile in virgin cycling female rats.

High-Fat, High-Sugar Diet Disrupts the Preovulatory Hormone Surge and Induces Cystic Ovaries in Cycling Female Rats.

Diet-induced obesity has been associated with various metabolic and reproductive disorders, including polycystic ovary syndrome. However, the mechanisms by which obesity influences the reproductive system are still not fully known. Studies have suggested that impairments in hormone signaling are associated with the development of symptoms such as acyclicity and ovarian cysts. However, these studies have often failed to address how these hormonal changes arise and how they might contribute to the progression of reproductive diseases. In the present study, we used a high-fat, high-sugar (HFHS) diet to induce obesity in a female rodent model to determine the changes in critical reproductive hormones that might contribute to the development of irregular estrous cycling and reproductive cycle termination. The HFHS animals exhibited impaired estradiol, progesterone (P4), and luteinizing hormone (LH) surges before ovulation. The HFHS diet also resulted in altered basal levels of testosterone (T) and LH. Furthermore, alterations in the basal P4/T ratio correlated strongly with ovarian cyst formation in HFHS rats. Thus, this model provides a method to assess the underlying etiology of obesity-related reproductive dysfunction and to examine an acyclic reproductive phenotype as it develops.

Hepatoprotective and Metabolic Effects of Dietary Soy Phytoestrogens against Hyper Caloric Diet in Cyclic Female Wistar Rats is Mediated through Estradiol Receptors

Hepatoprotective and Metabolic Effects of Dietary Soy Phytoestrogens against Hyper Caloric Diet in Cyclic Female Wistar Rats is Mediated through Estradiol Receptors

Influence of estrous cycle hormonal fluctuations and gonadal hormones on the ventilatory response to hypoxia in female rats.

Sex hormones may influence many physiological processes. Recently, we demonstrated that hormonal fluctuations of cycling female rats do not affect respiratory parameters during hypercapnia. However, it is still unclear whether sex hormones and hormonal fluctuations that occur during the estrous cycle can affect breathing during a hypoxic challenge. Our study aimed to evaluate respiratory, metabolic, and thermal responses to hypoxia in female rats on different days of the estrous cycle (proestrus, estrus, metestrus, and diestrus) and in ovariectomized rats that received replacement with oil (OVX), estradiol (OVX+E2), or a combination of estradiol and progesterone (OVX+E2P). Ventilation (V E), tidal volume (V T), respiratory frequency (fR), oxygen consumption (VO2), and V E/VO2 were not different during the estrous cycle in normoxia or hypoxia. Body temperature (Tb) was higher during estrus, but decreased similarly in all groups during hypoxia. Compared with intact females in estrus, gonadectomized rats also had lower Tb in normoxia, but not in hypoxia. OVX rats experienced a significant drop in the ventilatory response to hypoxia, but hormonal replacement did not restore values to the levels of an intact animal. Our data demonstrate that the different phases of the estrous cycle do not alter ventilation during normoxia and hypoxia, but OVX animals display lower ventilatory responses to hypoxia compared with ovary-intact rats. Because estradiol and progesterone replacement did not cause significant differences in ventilation, our findings suggest that a yet-to-be-defined non-steroidal ovarian hormone is likely to stimulate the ventilatory responses to hypoxia in females.

Nongenomic Actions of 17-β Estradiol Restore Respiratory Neuroplasticity in Young Ovariectomized Female Rats.

Gonadal steroids modulate CNS plasticity, including phrenic long-term facilitation (pLTF), a form of spinal respiratory neuroplasticity resulting in increased phrenic nerve motor output following exposure to acute intermittent hypoxia (aIH; three 5 min episodes, 10.5% O2). Despite the importance of respiratory system neuroplasticity, and its dependence on estrogen in males, little is known about pLTF expression or mechanisms of estrogen signaling in females. Here, we tested the hypotheses that (1) pLTF expression in young, gonadally intact female rats would be expressed during estrous cycle stages in which 17β-estradiol (E2) is naturally high (e.g., proestrus vs estrus), (2) pLTF would be absent in ovariectomized (OVX) rats and in physiological conditions in which serum progesterone, but not E2, is elevated (e.g., lactating rats, 3-10 d postpartum), and (3) acute E2 administration would be sufficient to restore pLTF in OVX rats. Recordings of phrenic nerve activity in female Sprague Dawley rats (3-4 months) revealed a direct correlation between serum E2 levels and pLTF expression in cycling female rats. pLTF was abolished with OVX, but was re-established by acute E2 replacement (3 h, intraperitoneal). To identify underlying E2 signaling mechanisms, we intrathecally applied BSA-conjugated E2 over the spinal phrenic motor nucleus and found that pLTF expression was restored within 15 min, suggesting nongenomic E2 effects at membrane estrogen receptors. These data are the first to investigate the role of ovarian E2 in young cycling females, and to identify a role for nongenomic estrogen signaling in any form of respiratory system neuroplasticity.SIGNIFICANCE STATEMENT Exposure to acute intermittent hypoxia induces phrenic long-term facilitation (pLTF), a form of spinal respiratory motor plasticity that improves breathing in models of spinal cord injury. Although pathways leading to pLTF are well studied in males and estradiol (E2) is known to be required, it has seldom been investigated in females, and underlying mechanisms of E2 signaling are unknown in either sex. We found that while ovariectomy abolished pLTF, it could be restored by acute systemic E2, or by intraspinal application of the membrane-impermeable E2 (BSA-conjugated E2; 15 min). The ability of nongenomic estrogen signaling within the cervical spinal cord to recover respiratory neuroplasticity in disorders of respiratory insufficiency suggests that membrane estrogen receptors may represent novel therapeutic targets to restore breathing in both sexes.

Ovarian hormones modify anxiety behavior and glucocorticoid receptors after chronic social isolation stress

Chronic social isolation could lead to a disruption in the Hypothalamic-Pituitary-Adrenal (HPA) axis, resulting in anxiety and depressive-like behaviors but cycling estrogens could modify these behaviors. The aim of this study was to determine if changes in ovarian hormones during the normal cycle could interact with social isolation to alter anxiety and depressive-like behaviors. In parallel, we examined the expression of glucocorticoid receptor (GR) and synaptic vesicle protein synaptophysin in the hippocampus and hypothalamus of Sprague Dawley normal cycling female rats. We assigned rats to either isolated or paired housing for 8 weeks. To assess anxiety and depressive-like behaviors, we used the open field test and forced swim test, respectively. Female rats were tested at either diestrus, estrus, or proestrus stage of the estrous cycle. After behaviors, rats were perfused and brains collected. Brain sections containing hippocampus and hypothalamus were analyzed using immunohistochemistry for synaptophysin and glucocorticoid receptor (GR) levels. We found an increase in depressive-like behaviors for isolated animals compared to paired housed rats, regardless of the estrous cycle stage. Interestingly, we found a decrease in anxiety behaviors in females in the estrus stage accompanied by a decrease in GR expression in hippocampal DG and CA3. However, no changes in synaptophysin were observed in any of the areas of studied. Our results support the beneficial effects of circulating ovarian hormones in anxiety, possibly by decreasing GR expression.

Sex differences in hepatic MCT1 and CD147 expression

PurposeMonocarboxylate transporter 1 (MCT) belongs to the solute carrier super family, and transports monocarboxylates such as ketone bodies, lactate and pyruvate, as well as drugs such as gamma‐hydroxybutyric acid. CD147 interacts with MCT1 as an ancillary protein for trafficking to the plasma membrane. Previously, it has been shown that MCT expression changes under different sex hormone conditions in skeletal muscle and Sertoli cells. However, it is unknown if MCT1 or CD147 demonstrates sex differences in the liver where MCT1 play an important role in drug disposition. The purpose of this study is to evaluate hepatic MCT1 and CD147 mRNA and protein expression in males, over the estrus cycle in female rats and in the absence of female sex hormones.MethodLiver samples were harvested from 6 groups of rats (N = 3 – 5 per group): females at the four stages of the estrus cycle (proestrus, estrus, metestrus, diestrus), ovariectomized (OVX) females and male Sprague‐Dawley rats. Estrus cycle stages of females were classified by vaginal lavage smear. Hepatic mRNA expression of MCT1 and CD147 were analyzed by qPCR. Whole cell and membrane protein expression of MCT1 and CD147 were evaluated by western blot.ResultsMCT1 mRNA expression was significantly lower (0.4 and 0.3 fold respectively) in proestrus and metestrus compared to control (male rats). OVX and male rats showed similar MCT1 mRNA and whole cell protein expression. Membrane MCT1 expression in proestrus, metestrus, and diestrus groups was significantly lower (21% – 42%) compared to OVX rats. MCT1 total and membrane protein expression were positively correlated (r = 0.69). Hepatic membrane bound ancillary protein CD147 in males was significantly higher (2.3 – 3 times) than other groups whereas mRNA and whole protein expression did not show any difference.ConclusionMCT1 mRNA expression is lower in the presence of female sex hormones indicating they play a role in reducing MCT1 mRNA expression in liver. Ovariectomy increased membrane MCT1 expression compared to female rats indicating female hormones negatively regulate MCT1 membrane expression. Significant sex differences were observed in membrane CD147 expression, whereas there was no difference in whole cell protein and mRNA levels demonstrating that androgens are involved in regulating CD147 membrane localization. This study reveals that hepatic MCT1 and CD147 expression and localization were regulated by sex hormones. Sex differences in hepatic MCT1 expression may lead to altered drug disposition of its substrates, so it is critical to understand the role of sex hormones and MCT1 regulation.